Dynamic Braking (DC Drives)

A. Dynamic Braking (DC Drives) --- slows the
motor by applying a resistive load across the
armature leads after disconnection from the
DC supply. This must be done while the
motor field is energized. The motor then acts
as a generator until the energy of the rotating
armature is dissipated. This is not a holding
brake.
Dynamic Braking (AC Drives) --- Since AC
motors do not have separate field excitation,
dynamic braking is accomplished by
continuing to excite the motor from the drive.
This causes a regenerative current to the
drive’s DC Intermediate Bus Circuit. The
Dynamic Brake resistors are then placed
across the DC bus to dissipate the power
returned. The brake resistor is usually
switched by a transistor or other power switch
controlled by the drive.